As sort of this interposer, there has been known a conventional wiring board which a light emitting element (LED chip) is mounted on and which has a high reflectivity (Patent Literature 1).
In the wiring board described in Patent Literature 1, gold films form a pattern by plating on an upper surface of a ceramic substrate.
The gold films are provided with an anode electrode and a cathode electrode that are connected to a circuit outside the wiring board without short-circuiting.
The wiring board is formed with a silver film, around a mounting section, on the gold films and almost all of a substrate surface which is the upper surface of the ceramic substrate and which the gold films are not formed on. A dielectric multilayer film is formed on the silver film.
In the wiring board, platinum films are under the gold films, and titanium films are under the platinum films and in contact with the ceramic substrate.
In a light emitting device with the wiring board, an LED chip is joined to the wiring board through alloy of gold and tin by flip-chip assembly.
What is desired in the field of interposers to be interposed between a light emitting element and a circuit board is cost reduction.